JP2013517360A - Method for producing polymer nanocomposite - Google Patents

Abstract

  The present invention relates to a nanocomposite comprising a rubber ionomer produced by an energy efficient, environmentally favorable method using a common medium for solution polymerization, rubber bromination and optionally subsequent polymer nanocomposite formation. The present invention relates to a material manufacturing method. The polymer nanocomposite material according to the present invention exhibits high oxygen impermeability.

Description

  The present invention relates to a polymer nanoparticle comprising a butyl rubber ionomer produced by an energy efficient, environmentally-friendly method using a common medium for solution polymerization, rubber bromination and optionally subsequent polymer nanocomposite formation. The present invention relates to a method for manufacturing a composite material. The polymer nanocomposite material according to the present invention exhibits high oxygen impermeability.

The term “butyl rubber” as used herein generally means a copolymer of C _{4 to} C ₇ isoolefin, C _{4 to} C ₁₄ conjugated diene and optionally other copolymerizable monomers, unless otherwise defined. Including them. The term “bromobutyl rubber” as used herein generally means and includes brominated butyl rubber unless otherwise defined. An exemplary and preferred example of butyl rubber is a rubber obtained by copolymerization of isoprene and isobutylene, also referred to herein as IIR. The brominated analog is also referred to as BIIR.

  Poly (isobutylene-co-isoprene), or IIR, is a synthetic elastomer commonly known as butyl rubber that has been produced since the 1940s by random cationic copolymerization of isobutylene with small amounts of isoprene. The resulting commercially available IIR has a multiolefin content of 1-2 mol%. As a result of its molecular structure, IIR has excellent air impermeability, high loss modulus, oxidation stability and long-term fatigue resistance (see (Non-Patent Document 1)).

  Treatment of bromobutyl rubber with nitrogen and / or phosphorus-based nucleophiles has been shown to lead to the formation of ionomers with interesting physical and chemical properties that depend inter alia on their initial isoprene content. (See (Patent Document 1), (Patent Document 2), (Non-Patent Document 2), (Non-Patent Document 3).

  Polymer nanocomposites are a rapidly expanding interdisciplinary field that presents a radical alternative to conventional filled polymers or polymer blends. Polymer nanocomposites are typically formed by the incorporation of nanosize fillers into the ionomer matrix. Hybrid materials reinforced with neat and / or organically modified high aspect ratio plate-like fillers represent the most widely studied class of nanocomposites. The strong interfacial interaction between the dispersion layer and the polymer matrix results in improved mechanical and barrier properties over conventional composite materials. Among many areas of polymer nanocomposite research, the tire industry is particularly interested in high aspect ratio fillers. Recent studies have shown that the addition of high aspect ratio fillers to tire innerliner formulations has shown an increase in impermeability of up to 40% (e.g. (Patent Document 3) and (Patent Document 4). Refer to).

  Maximizing high aspect ratio fillers to their full potential requires precise morphology and makes the choice of both polymer and filler critical. Polymer intercalation to the platelet gallery in the rubber matrix, platelet delamination and delamination and plate anisotropic alignment must be achieved. In order to achieve at least intercalation and delamination, it is advantageous to establish a chemical bond between the polymer matrix and the filler surface.

  Ionomers, especially butyl ionomers, used to produce polymer nanocomposites are typically produced in a multi-step procedure including slurry polymerization, solution halogenation and kneading reactions to form ionomers and nanocomposites. Is done.

In conventional slurry processes for producing bromobutyl rubber, isobutylene and isoprene monomers are either aluminum-based starting systems, typically either aluminum trichloride (AlCl ₃ ) or ethylaluminum dichloride (EtAlCl ₂ ). Is first polymerized in a polar halohydrocarbon medium, such as methyl chloride. Butyl rubber is almost insoluble in this polar medium and exists as suspended particles, so this process is commonly referred to as a slurry process. The residual monomer and polymerization medium are then steam distilled from the butyl rubber before it is dissolved in a brominated medium, typically a non-polar medium such as hexane. The bromination process ultimately produces the final brominated product. The conventional method therefore uses separate polymerization and bromination steps using two different media. The use of polar media for polymerization and nonpolar media for bromination requires intermediate stripping and dissolution steps and is inefficient from an energy standpoint.

  The step of separating monomer and methyl chloride from the butyl polymer is performed prior to bromination to avoid the formation of highly toxic by-products from the reaction of bromine with residual monomer. The normal boiling points of the components used in this process are methyl chloride, -24 ° C; isobutylene, -7 ° C; and isoprene, 34 ° C. Any stripping process that removes the heavier residual monomer (isoprene) will also remove essentially all of the methyl chloride and isobutylene. The process of removing all unreacted components from the rubber slurry requires a significant amount of energy. The higher molecular weight (and hence higher boiling point) of the brominated monomer also makes it impossible to remove these species after the bromination process.

  Solution processes for the polymerization of butyl rubber have been known for many years and are practiced commercially in Russia. An example of a solution process is described in US Pat. No. 6,057,086, which discloses the use of iso-pentane as a preferred polymerization medium. Polymers produced using the above method are not halogenated. Although bromination could theoretically be performed in iso-pentane, the presence of residual monomers (isobutylene and isoprene) would lead to the formation of the aforementioned unwanted side products during bromination. Removal of unreacted monomer is a challenge for such methods and has not yet been solved. Although it would be desirable to remove the monomer by distillation, the boiling point of iso-pentane (28 ° C) is lower than that of the heavier residual isoprene monomer (34 ° C), so this type of separation is not possible. is there. Even if pure n-pentane (boiling point 36 ° C.) was used as the medium, the difference in boiling points would not be sufficient to allow effective removal of isoprene using distillation techniques. As a result, any residual monomer and medium will have to be stripped together from the butyl rubber, as in the slurry process, with the rubber subsequently re-dissolved for bromination. This is actually more energy intensive than the conventional slurry process bromination. The use of iso-pentane as a common medium for producing bromobutyl rubber is therefore impractical using conventional solution methods.

  The use of hexane, i.e. C6 medium, as the polymerization medium in the solution process is known in the art. However, the viscosity of the polymer solution is strongly dependent on the viscosity of the medium used. Because the viscosity of the C6 medium is much higher than that of the C5 medium for a given molecular weight and polymer solids level, the resulting viscosity of the polymer solution is also higher. This limits the polymer solids to relatively low levels when C6 is used as a solvent, otherwise the solution becomes too viscous for good heat transfer, pumping and handling. The overall economics of the process strongly depend on the level of polymer solids in the solution or suspension coming out of the polymerization reactor; higher solids levels mean higher conversion and improved economics . In order to produce materials with sufficiently high molecular weight for commercial purposes, it is necessary in butyl polymerization to use relatively low temperatures, often below -80 ° C. These low temperatures exacerbate the problem of high solution viscosity and lead to even lower solids levels. In the solution process, it is therefore very difficult to achieve an economical solids level (conversion) at the desired temperature (molecular weight) due to the high viscosity when hexane is used as the solvent.

  (Patent Document 6) discloses a method in which the product from a conventional slurry polymerization process is mixed with hexane to produce a crude rubber solution or cement. Hexane is still subdivided into the methyl chloride / monomer mixture and added to the methyl chloride-rubber slurry after leaving the polymerization reactor to dissolve the rubber in hexane while suspended. A distillation process is then used to remove recycle methyl chloride and residual isobutene and isoprene monomers, leaving only the rubber in the hexane solution ready for halogenation. This so-called “solvent replacement” process still requires that all of the original media left with the rubber after the polymerization stage be removed. The energy requirements are essentially the same as in the conventional method. No common solvent is used for both polymerization and bromination.

European Patent Application Publication No. 1 922 361 A European Patent Application Publication No. 1 913 077 A US Pat. No. 7,019,063 European Patent Application Publication No. 1 942 136 A

Chu, C.I. Y. and Vukov, R.A. , Macromolecules, 18, 1423-1430, 1985. Parent, J. et al. S. Liskova, A .; Whitney, R .; A. Parent, J .; S. Liskova, A .; Resendes, R .; Polymer 45, 8091-8096, 2004 Parent, J. et al. S. Penciu, A .; Guillen-CasteUanos, S .; A. Liskova, A .; Whitney, R .; A. Macromolecules 37, 7477-7383, 2004

  Therefore, there remains a need for an efficient and environmentally preferred method of producing brominated rubber that can then be further converted to nanocomposites.

a) 40:60 to 95: 5, preferably 50:50 to 85:15, more preferably 61:39 to 80:20 by weight ratio of monomer mixture to common aliphatic medium,
A common aliphatic medium comprising at least 50% by weight of one or more aliphatic hydrocarbons having a boiling point in the range of 45 ° C. to 80 ° C. at a pressure of 1013 hPa, and at least one monoolefin monomer, at least one multiolefin Providing a reaction medium comprising a monomer mixture comprising monomers and no or at least one other copolymerizable monomer;
b) polymerizing the monomer mixture in the reaction medium to form a rubber solution comprising a rubber polymer that is at least substantially dissolved in a medium comprising the common aliphatic medium and the remaining monomers of the monomer mixture;
c) separating the residual monomer of the monomer mixture from the rubber solution to form a separated rubber solution comprising a rubber polymer and a common aliphatic medium;
d) brominating the rubber polymer in the separated rubber solution to obtain a solution containing the brominated rubber polymer and a common aliphatic medium;
e) reacting the brominated rubber polymer obtained in step d) with at least one nitrogen and / or phosphorus-containing nucleophile; f) adding a filler to the ionomer obtained in step e); There is provided a method for producing a polymer nanocomposite comprising at least a step of mixing an ionomer with an ionomer to form an uncured nanocomposite and g) optionally curing the nanocomposite.

  The scope of the present invention includes all possible combinations of definitions, parameters and illustrations given herein, whether general or within the field of preference.

  As used herein, the term “at least substantially dissolved” means at least 70% by weight of the rubber polymer obtained by step b), preferably at least 80% by weight, more preferably at least 90% by weight, Even more preferably, it means that at least 95% by weight is dissolved in the medium.

  In an embodiment of the invention, the polymerization according to step b) and the provision of the solution according to step a) are accomplished using a solution polymerization reactor. Suitable reactors are known to those skilled in the art and include flow-through polymerization reactors.

  The present invention advantageously provides polymer nanocomposites having reduced gas permeability and / or excellent tensile strength. The nanocomposite material of the present invention is particularly useful for tire inner liner applications, for example.

  Step c) of the process may use distillation to separate unreacted residual monomers, i.e. isoolefin monomers and multiolefin monomers, from the medium. This reduces the formation of undesirable halogenated byproducts from unreacted monomers. The process is conducted at a moderate or relatively high ratio of monomer to common aliphatic medium. Typically, isoolefin monomers have a much lower viscosity than common aliphatic media, and therefore higher monomer levels result in a lower overall viscosity. The overall energy efficiency and raw material utilization of the process reflects the need to separate the rubber from the first diluent or solvent used for the polymerization and then re-dissolve it in the second solvent for bromination. Improved by eliminating and recycling the bromide resulting from bromination back to the brominating agent. The integrated process according to the present invention therefore provides improved energy and raw material efficiency and a reduction in the number of process steps as compared to conventional non-integrated processes for producing brominated butyl rubber.

  To summarize the present invention, its preferred embodiment is described with respect to FIG.

FIG. 2 shows a process flow diagram for the method according to the invention using purification of unreacted monomers after separation from the polymer solution and optional recycling.

Referring to FIG. 1, a solution polymerization reactor 40 includes an optional heat exchanger 10, preferably a recuperative heat exchanger, and a feed cooler 20 for the monomer M containing isoprene and isobutylene. A feed as well as a common aliphatic medium S is provided. The monomers may be either premixed with the common aliphatic medium or mixed in the polymerization reactor 40. A catalyst solution comprising a carbocationic initiator-activator system of the type used for butyl rubber polymerization (eg, trivalent metal species such as aluminum (organo) halides, and a small amount of water) It is premixed with the common aliphatic medium S in the preparation device 30 and is also introduced into the reactor 40. As a result, solution polymerization occurs in the polymerization reactor 40. A solution polymerization reactor 40 of a type suitable for use in the integrated process is incorporated herein by reference, along with process control and operating parameters of such a reactor, for example, European Patent Application No. 0 053 585. The conversion is allowed to proceed to the desired extent and then a reaction terminator, for example an alcohol such as water or methanol, is added in the mixer 50 into the reactor discharge stream comprising the common aliphatic medium S, unreacted monomer M and butyl rubber IIR. And mixed. The resulting polymer solution containing unreacted monomers M, i.e. isoprene and isobutylene, common aliphatic medium S and butyl rubber IIR, is passed through recuperated heat exchanger 10 where it is fed to the reactor. While at the same time serve to cool these feeds before they enter the final feed cooler 20. The warmed polymer solution is then directed to a distillation column 60 for removal of unreacted monomers. After unreacted monomers I are separated as recycling flow M _R, which exits from the top of column 60, separated polymer solution (S, IIR) is a solution bromination reactor exits the bottom of the column 60 Enter 70. Additional common aliphatic medium S and / or water W may be provided to the bromination reactor 70 to provide the desired conditions for bromination. It is important to point out that the same common aliphatic medium used for polymerization entrains butyl rubber throughout the process until bromination and that there is no need to separate the polymer from the solvent prior to bromination. . Brominating agent B (as described herein below) is also provided to bromination reactor 70. Brominated butyl rubber (BIIR) exits the reactor in solution (S, BIIR) and then after neutralization and washing, typically using reactor 80, in solution or after removal of the common aliphatic medium? Is converted to the corresponding ionomer (ION) by addition of nitrogen and / or phosphorus containing nucleophile NUC and filler F, and further to the corresponding nanocomposite (NC). The resulting nanocomposite (NC) is then subjected to general finishing and drying procedures. Common aliphatic medium removed either or in front or the finishing step of forming the ionomer and / or nanocomposites, sent to solvent recovery 110 as recycling stream S _R prior to introduction to solvent purification section 120 It is done. Before or additional common aliphatic medium S _F purification 120 or, if the medium has already been prepurified may be added later. The purified common aliphatic medium is recycled back to the recuperated heat exchanger 10 and the final feed cooler 20 for reuse in the process. Unreacted monomer separated from the polymer solution in the distillation column 60 is sent to a monomer recovery unit 90 as a recycle stream M _R, then before the recycled back to the recuperative heat exchanger 10 and feed cooler 20 To be purified in the monomer purification section 100. Or before the addition of fresh monomer M _F are monomer purification 100, if the monomer is prepurified may be added at either or later. The use of a common aliphatic medium for both polymerization and bromination, and optionally even for the conversion to ionomers, reduces the environmental impact of this integrated process compared to conventional approaches and provides economic results. Improve.

  The description of the method presented herein above is exemplary and applies to all common aliphatic media compositions as well as to all monomer and product compositions described herein. be able to.

  It is within the scope of the present invention that the composition of the common aliphatic medium may have a slightly varied composition before and after removal of unreacted monomer due to the different boiling points of its components.

  The monomer mixture used to produce the rubber polymer by solution polymerization is such that the individual monomers have a boiling point below 45 ° C. at 1013 hPa, preferably below 40 ° C. at 1013 hPa, and the monomer mixture is less than the common aliphatic medium. It is not limited to a specific isoolefin as long as it has a low viscosity. However, isoolefins in the range of 4-5 carbon atoms, such as iso-butene, 2-methyl-1-butene, 3-methyl-1-butene, 2-methyl-2-butene or mixtures thereof, preferable. The most preferred isoolefin is isobutene.

  The monomer mixture is a specific multiolefin, provided that the individual monomers have a boiling point of less than 45 ° C. at 1013 hPa, preferably less than 40 ° C. at 1013 hPa, and that the monomer mixture has a lower viscosity than the common aliphatic medium. It is not limited. Multiolefins known by those skilled in the art to be copolymerizable with the above-mentioned isoolefins can be used. However, multiolefins containing dienes, in particular conjugated dienes, in the range of 4 to 5 carbon atoms, such as isoprene, butadiene or mixtures thereof, are preferably used. The most preferred multiolefin is isoprene.

  In one embodiment, the monomer mixture for the production of the rubber polymer, preferably butyl rubber, is at least in the range of 80.0 wt% to 99.9 wt%, preferably 92.0 wt% to 99.5 wt%. One, preferably one iso-olefin monomer and at least one, preferably one multiolefin, in the range of 0.5 wt% to 20.0 wt%, preferably 0.5 wt% to 8.0 wt% Monomers may be included. More preferably, the monomer mixture is at least one in the range 95.0 wt% to 98.5 wt%, preferably at least one iso-olefin monomer and at least 1.5 wt% to 5.0 wt%. One, preferably one multiolefin monomer is included. Most preferably, the monomer mixture is at least one in the range of 97.0% to 98.5% by weight, preferably one isoolefin monomer and at least 1 in the range of 1.5% to 3.0% by weight. One, preferably one multiolefin monomer.

  The ranges indicated above in the preferred embodiment of the invention apply to monomer mixtures in which the isoolefin is isobutene and the multiolefin is isoprene.

  In one embodiment, the multiolefin content of the butyl rubber produced according to the present invention is, for example, in the range of 0.5 mol% to 20.0 mol%, preferably 0.5 mol% to 8.0 mol%, More preferably in the range of 1.0 mol% to 5.0 mol%, even more preferably in the range of 1.5 mol% to 5 mol%, even more preferably 1.8 mol% to 2.2 mol%. % Range.

  In another embodiment, the multiolefin content of the butyl rubber produced according to the present invention is, for example, preferably in the range of 3.5 mol% to 20.0 mol%, more preferably 3.5 mol% to 6. It is in the range of 0 mol%, even more preferably 3.5 mol% to 5.0 mol%.

  One way to overcome the aforementioned viscosity problem is by selecting a high monomer to solvent ratio in the polymerization process. Although a mass ratio of monomer to aliphatic hydrocarbon solvent of 60:40 or less has been used in the prior art, in one aspect the present invention is for example 61: 39-80: 20, preferably 65: 35-70: Utilize a higher ratio of 30. It is primarily a C4 compound and has a lower viscosity than common aliphatic media. The presence of higher monomer levels lowers the solution viscosity to an acceptable limit, and also allows higher solids levels to be achieved during polymerization. It allows to reach an acceptable molecular weight at higher temperatures when is used. The use of higher temperatures in turn reduces the solution viscosity and allows for higher polymer solids levels in the solution.

  Another way in which the aforementioned viscosity problem can be overcome is by selecting a common aliphatic medium as the solvent. Solvents having a higher content of or consisting of compounds having a boiling point of 45 ° C. or lower at 1013 hPa have a boiling point close to that of the monomer so that separation of the monomer from the solution will result in significant solvent removal. Would have.

  The use of a solvent with a high content of or consisting of compounds having a boiling point above 80 ° C. at 1013 hPa will make separation from the rubber after bromination difficult. The solution viscosity provided by the use of such solvents is also significantly higher than with common aliphatic media, even when provided with the high monomer to solvent ratios described above, making the solution more difficult to handle and reacting Hinder heat transfer in the chamber.

  In a preferred embodiment of the present invention, the common aliphatic medium is 45% at a pressure of 1013 hPa of at least 80% by weight, preferably at least 90% by weight, even more preferably at least 95% by weight, and even more preferably at least 97% by weight. One or more aliphatic hydrocarbons having a boiling point in the range of from 0C to 80C. Aliphatic hydrocarbons having a boiling point in the range of 45 ° C. to 80 ° C. at a pressure of 1013 hPa include cyclopentane, 2,2-dimethylbutane, 2,3-dimethylbutane, 2-methylpentane, 3-methylpentane, n -Hexane, methylcyclopentane and 2,2-dimethylpentane.

The common aliphatic medium is at least substantially under polymerization conditions such as heptane and octane, other aliphatic hydrocarbons such as propane, butane, n-pentane, cyclohexane having a boiling point above 80 ° C. at a pressure of 1013 hPa. Other compounds that are chemically inert, and halohydrocarbons such as methyl chloride and other chlorinated aliphatic hydrocarbons that are at least substantially inert under the reaction conditions, and, for example, the formula C _x H _y F _z (Wherein x is an integer of 1 to 20, or 1 to 1, preferably 1 to 3, wherein y and z are integers and are at least 1) May be included.

  In another preferred embodiment of the present invention, the common aliphatic medium is substantially free of halohydrocarbons.

  As used herein, the term “substantially free” means less than 2% by weight, preferably less than 1% by weight, more preferably less than 0.1% by weight, and even more preferably the absence of halohydrocarbons. It means the content of halohydrocarbon in the aliphatic medium.

  The preferred ratio of monomer to hydrocarbon solvent cannot be calculated in advance, but can easily be determined by very few routine experiments. Although increasing the amount of monomer should reduce the solution viscosity, making an accurate theoretical prediction of the extent of the decrease is the interaction of the various components of the solution at the concentration and temperature used in the method. It is not feasible due to some extent to the complex influence on the viscosity of

  In one embodiment, the process temperature is in the range of -100 ° C to -40 ° C, preferably in the range of -95 ° C to -65 ° C, more preferably in the range of -85 ° C to -75 ° C. More preferably, it exists in the range of -80 degreeC--75 degreeC.

  Higher temperatures are desirable in that energy usage for cooling and pumping is reduced (due to lower viscosity at higher temperatures), but this is not as commercially desirable. Generally results in low molecular weight polymers. However, due to the use of a high monomer to solvent ratio in the present invention, a reduced but still acceptable molecular weight can be obtained at higher temperatures.

  Therefore, in alternative embodiments, lower than -50 ° C to -75 ° C, preferably from -55 ° C to -72 ° C, more preferably from -59 ° C to -70 ° C, and even more preferably from -61 ° C to Temperatures in the range of -69 ° C are used while still obtaining the desired molecular weight butyl rubber.

  The weight average molecular weight of the butyl rubber polymer produced using the method according to the invention is typically 200 to 1000 kg / mol, preferably 200 to 700 kg / mol, more preferably as measured before bromination. It is in the range of 325-650 kg / mol, even more preferably 350-600 kg / mol, even more preferably 375-550 kg / mol, even more preferably 400-500 kg / mol. Unless otherwise noted, molecular weights are obtained using gel permeation chromatography in tetrahydrofuran (THF) solution using polystyrene molecular weight standards.

  The viscosity of the solution upon discharge from the reactor 40 is typically and preferably less than 2000 cP, preferably less than 1500 cP, more preferably less than 1000 cP. The most preferable range of the viscosity is 500 to 1000 cP. Unless otherwise specified, the viscosity is a viscosity measured with a cone-plate type rotary rheometer (Haake). All indicated viscosities refer to extrapolated zero shear viscosity.

  The solids content of the solution obtained after polymerization is preferably 3-25% by weight, more preferably 10-20% by weight, even more preferably 12-18% by weight, even more preferably 14-18% by weight, More preferably it is in the range of 14.5 to 18% by weight, even more preferably 15 to 18% by weight, most preferably 16 to 18% by weight. As noted above, higher solids are preferred but with increased solution viscosity. The higher monomer to solvent ratio used in the process allows higher solids content than in the past to be achieved, and advantageously also allows the use of a common aliphatic medium for both polymerization and bromination To.

  As used herein, the term “solids” means the weight percent of the polymer obtained by step b), ie in the polymerization, and present in the rubber solution.

  In step c), unreacted residual monomer is removed from the polymerized solution, preferably using a distillation process. Distillation processes for separating liquids of different boiling points are well known in the art and are incorporated herein by reference, for example, Encyclopedia of Chemical Technology, Kirk Othmer, 4th Edition, pp. 8-311.

  The degree of separation greatly depends on the number of trays used in the column. An acceptable and preferred level of residual monomer in the solution after separation is less than 20 parts per million by weight. About 40 trays have been found to be sufficient to achieve this degree of separation. The separation of the common aliphatic medium from the monomer is not critical, for example components of the common aliphatic medium with a content of 10% by weight or less are allowed in the overhead stream from the distillation process. The In a preferred embodiment, the content of common aliphatic medium components in the overhead stream from the distillation process is less than 5% by weight, more preferably less than 1% by weight.

  With reference to FIG. 1, the method of the present invention preferably includes purification of unreacted monomers separated from the polymerization solution using a distillation column 60. A purifier 100 may be provided for this purpose; alternatively, the purification can be performed off-site in a separate purifier. Purified monomers are usually recycled back into this process and mixed with fresh monomers; however, they may alternatively be utilized in different processes or sold separately. Preferred embodiments of the method include these optional purification and recycling steps to achieve an advantageous overall process economy.

  Monomer purification may be performed by passing through an adsorbent tower containing a suitable molecular sieve or alumina-based adsorbent. To minimize interference with the polymerization reaction, the total concentration of water and substances such as alcohol and other organic oxygenates that act as poisons for this reaction is preferably less than about 10 parts per million by weight. Is lowered. The proportion of monomer that is available for recycling depends on the degree of conversion obtained during the polymerization process. For example, taking the monomer to common aliphatic medium ratio of 66:34, if the solids level in the resulting rubber solution is 10%, 85% of the monomer is available to be returned to the recycle stream. is there. If the solids level is increased to 18%, 73% of the monomer is available for recycling.

  After removal of unreacted residual monomer, the butyl polymer is brominated in step d). Brominated butyl rubber is produced using a solution phase technique. A “cement” containing a solution of butyl rubber dissolved in the common aliphatic medium used during the polymerization process is treated with a brominating agent used either in the absence or presence of a reoxidant.

  Suitable reoxidizers include peroxides and peroxide forming materials as exemplified by the following materials: hydrogen peroxide, sodium chlorate, sodium bromate, sodium hypochlorite or bromine Sodium oxide, oxygen, nitrogen oxide, ozone, urea peroxydate, pertitanic acid, perzirconic acid, perchromic acid, permolybdic acid, pertungstic acid, perunanic acid, perboric acid, perphosphoric acid Acids, such as perpyrolic acid, persulfate, perchloric acid, perchlorate and periodic acid, or mixtures of the aforementioned oxidizing agents.

  A supplemental solvent, including, for example, a fresh common aliphatic medium, and / or water may be added to the separated rubber solution to form a cement having the desired properties for bromination.

  Bromination in the common aliphatic medium used during the polymerization process eliminates the need for separating the polymer from the polymerization medium and then re-dissolving it in a different medium for bromination. It saves energy advantageously compared to the slurry method.

  Preferably, the amount of brominating agent is in the range of about 0.1 to about 20% by weight of the polymer, preferably 0.1 to 8%, even more preferably about 0.5% to about 4%. %, Even more preferably from about 0.8% to about 3%, even more preferably from about 1.5% to about 2.5%, most preferably even more preferably from 1.5 to It is in the range of 2.5% by weight.

  In another embodiment, the amount of brominating agent is 0.2-1.2 times the molar amount of double bonds contained in the butyl polymer, preferably 0.8-1.2 times this molar amount. is there.

The brominating agent may include interhalogen compounds such as elemental bromine (Br ₂ ), bromine chloride (BrCl) and / or their organic halide precursors such as dibromo-dimethylhydantoin, N-bromosuccinimide, and the like. The most preferred brominating agent comprises bromine. Even more preferably bromine is used as brominating agent.

  The bromination process may be operated at a temperature of 10 ° C. to 90 ° C., preferably 20 ° C. to 80 ° C., and the reaction time may be 1 to 10 minutes, preferably 1 to 5 minutes. The pressure in the bromination reactor may be 0.8 to 10 bar.

  The amount of bromination during this procedure may be controlled so that the final polymer has the preferred amount of bromine described hereinabove. The particular mode of polymer bonding the halogen is not particularly limited and those skilled in the art will appreciate that modes other than those described above may be used while achieving the benefits of the present invention. For additional details and alternative embodiments of the solution phase bromination process, see, for example, Ullmann's Encyclopedia of Industrial Chemistry (Fifth, Completely Revised Edition, Volume E 23, “Rubber Technology” (Third Edition) by Chapter Morton, Chapter 10 (Van Northland Reinhold Company, Copyright 1987), especially pp. See 297-300.

  According to step e), the brominated butyl rubber polymer obtained in step d) is reacted with at least one nitrogen and / or phosphorus containing nucleophile.

  After completion of the bromination reaction in step d), the polymer is subjected to conventional methods such as neutralization with dilute caustic solutions, removal of solvents such as by washing and steam distillation or precipitation using lower alcohols such as isopropanol, followed by drying. May be recovered.

  Quaternization and ionomer formation can be easily achieved by reaction kneading, which can be performed in an internal mixer, for example, at a temperature and residence time sufficient to carry out the reaction. Alternatively, the reaction may be carried out in solution under optionally elevated pressure and temperature.

  When solution techniques are applied, the rubber solution containing the bromobutyl rubber polymer obtained in step d) and the common aliphatic medium is neutralized with an aqueous basic material, for example a dilute aqueous solution of sodium hydroxide, Separating the organic phase comprising the bromobutyl rubber polymer and the common aliphatic medium obtained by the step, and optionally reacting the solution with at least one nitrogen and / or phosphorus containing nucleophile after an additional drying step It is preferable to make it.

  As used herein, the term “nucleophile” means a compound having a lone pair of electrons placed on nitrogen or phosphorus that can form a covalent bond to form a phosphonium or ammonium ion.

Preferred nitrogen and / or phosphorus containing nucleophiles are of formula I
AR ¹ R ² R ³ (I)
(Where
A means nitrogen or phosphorus,
R ¹ , R ² and R ³ are independently selected from the group consisting of C ₁ -C ₁₈ alkyl, C ₆ -C ₁₅ arylalkyl or C ₅ -C ₁₄ aryl)
belongs to.

C ₁ -C ₁₈ alkyl means a linear, cyclic, branched or unbranched alkyl radical optionally further substituted with a hydroxyl or alkoxy group. The same applies to the alkyl moiety of the _C 6 _{-C 15} arylalkyl radicals.

C ₅ -C ₁₄ aryl is not only a carbocyclic radical, but also zero, 1, 2, or 3 carbon atoms of each aromatic ring, but at least one carbon atom in the total radical is nitrogen, sulfur or Also meant are heteroaromatic radicals substituted with a heteroatom selected from the group of oxygens.

  Alkoxy means a linear, cyclic or branched or unbranched alkoxy radical.

Preferred nucleophiles of formula (I) are those in which two or three of the residues R ¹ , R ² and R ³ are identical.

  More preferred nucleophiles of formula (I) are trimethylamine, triethylamine, triisopropylamine, tri-n-butylamine, trimethylphosphine, triethylphosphine, triisopropylphosphine, tri-n-butylphosphine, triphenylphosphine, 2-dimethyl. Aminoethanol, 1-dimethylamino-2-propanol, 2- (isopropylamino) ethanol, 3-dimethylamino-1-propanol, N-methyldiethanolamine, 2- (diethylamino) ethanol, 2-dimethylamino-2-methyl- 1-propanol, 2- [2- (dimethylamino) ethoxy] ethanol, 4- (dimethylamino) -1-butanol, N-ethyldiethanolamine, triethanolamine, 3-diethylamino-1- Lopanol, 3- (diethylamino) -1,2-propanediol, 2-{[2- (dimethylamino) ethyl] methylamino} ethanol, 4-diethylamino-2-butyn-1-ol, 2- (diisopropylamino) Ethanol, N-butyldiethanolamine, N-tert-butyldiethanolamine, 2- (methylphenylamino) ethanol, 3- (dimethylamino) benzyl alcohol, 2- [4- (dimethylamino) phenyl] ethanol, 2- (N- Ethylanilino) ethanol, N-benzyl-N-methylethanolamine, N-phenyldiethanolamine, 2- (dibutylamino) ethanol, 2- (N-ethyl-Nm-toluidino) ethanol, 2,2 ′-(4- Methylphenylimino) diethanol, tris [2 A mixture of (2-methoxyethoxy) ethyl] amine, 3- (dibenzylamino) -1-propanol or the aforementioned nucleophiles.

  The amount of nucleophile reacted with the bromobutyl rubber obtained in step c) is, for example, preferably 0.05 to 5 molar equivalents, based on the total molar amount of allyl halide present in the bromobutyl polymer. Is in the range of 0.1 to 4 molar equivalents, more preferably 0.2 to 3 molar equivalents.

  The brominated polymer and nucleophile can be reacted, for example, for about 0.5 to 90 minutes.

  In another embodiment, the nanocomposite is produced in situ by reaction of the bromide with at least one nitrogen and / or phosphorus based nucleophile in the presence of a filler.

  In this case, steps e) and f) are performed simultaneously.

  Since the nucleophile preferably reacts with the allyl bromide functionality of bromobutyl rubber, the resulting ionomer moiety is a repeating unit derived from allyl bromide. The total content of ionomer moieties in the butyl ionomer can therefore not exceed the starting amount of allyl bromide in the bromobutyl polymer; however, there may be residual allyl bromide and / or residual multiolefin. According to the present invention, the resulting ionomer can also have an ionomer moiety and an allylic halogen with residual multiolefin present in the range of 0.2 to 5 mol%, even more preferably 0.5 to 0.8 mol%. The total molar amount of fluoride functionality is present in the range of 0.05 to 20.0 mol%, more preferably 0.2 to 1.0 mol%, even more preferably 0.5 to 0.8 mol%. Or a mixture of polymer-bound ionomer moieties and allylic halides. The residual allyl bromide can be present in an amount from 0.1 mol% up to an amount not exceeding the original allyl bromide content of the bromobutyl polymer used to produce the butyl ionomer. Residual multiolefin may be present in an amount from 0.1 mol% up to an amount not exceeding the original multiolefin content of the butyl polymer used to produce the halobutyl polymer. Typically, the ionomer has a residual multiolefin content of at least 0.4 mol%, preferably at least 0.6 mol%, more preferably at least 1.0 mol%, and even more preferably at least 2.0 mol%. Even more preferably, it is at least 3.0 mol%, even more preferably at least 4.0 mol%.

  In an embodiment of the present invention, the filler is selected from the group of high aspect ratio fillers.

  As used herein, the term “high aspect ratio” means an aspect ratio of at least 1: 3, where the aspect ratio is the average diameter of a circle in the same area as the plane of the plate versus the average thickness of the plate. Is defined as the ratio of The aspect ratio for acicular and fibrous fillers is the ratio of length to diameter.

  The filler may comprise a non-circular or non-same dimension material with a plate-like or needle-like structure. Preferred high aspect ratio fillers have an aspect ratio of at least 1: 5, more preferably at least 1: 7, and even more preferably from 1: 7 to 1: 250. The filler according to the present invention has an average particle size in the range of 0.001 to 100 microns, preferably 0.005 to 50 microns, more preferably 0.01 to 10 microns.

  Suitable fillers have a BET surface area of 5 to 200 square meters per gram, measured according to DIN (Deutsche Industry Norm) 66131.

In a preferred embodiment, the high aspect ratio filler is selected from the group consisting of nanoclays, preferably organically modified nanoclays. The present invention is not limited to specific nanoclays; natural powdered smectite clays such as sodium or calcium montmorillonite or synthetic clays such as hydrotalcite and laponite are preferred as starting materials. Organic modified montmorillonite nanoclay is particularly preferred. Clay is generally obtained by replacing onium ions with transition metals, as is known in the art, to provide the clay with surfactant functionality that aids in dispersion of the clay within the hydrophobic polymer environment. Preferably it is modified. Preferred onium ions are phosphorus-based (eg, phosphonium ions) and nitrogen-based (eg, ammonium ions) and contain functional groups having 2 to 20 carbon atoms (eg, NR ₄ ⁺ -MMT).

  The clay is preferably provided with a nanometer scale particle size, preferably less than 25 μm by volume, more preferably 1-50 μm, even more preferably 1-30 μm, and even more preferably 2-20 μm.

  In addition to silica, preferred nanoclays may also contain a fraction of alumina. The nanoclay may contain 0.1 to 10 wt% alumina, preferably 0.5 to 5 wt%, more preferably 1 to 3 wt% alumina.

Examples of preferred commercially available organic modified nanoclays suitable for use as high aspect ratio fillers according to the present invention are the trade names Cloisite® Clay 10A, 20A, 6A, 15A, 30B, or 25A. It is sold at. Other examples of high aspect ratio fillers include hydrofiltite clays such as Polyfil 80 ^™ , Mistron Vapor ^™ , Mistron HAR ^™ , Mistron CB ^™ and Perkalite LD, or Perkalite F100.

  The high aspect ratio filler is present in the nanocomposite in an amount of 1-80 phr, more preferably 2-20 phr, and even more preferably 5-10 phr.

  Nanocomposites may be formed by adding fillers to bromobutyl rubber prior to reaction to form ionomers, thereby producing in situ ionomer nanocomposites, or using conventional compounding techniques. It may be formed by adding a filler to the preformed ionomer. Alternatively, the ionomer can be formed in situ, followed by the addition of nanoclay in solution to form the ionomer nanocomposite.

  The nanocomposite raw materials may be mixed together using, for example, an internal mixer, such as a Banbury mixer, a small internal mixer, such as a Haake or Brabender mixer, or a two-roll mill mixer. However, care should be taken that no undesired pre-crosslinking (scorch, also known as a precursor of gel formation) occurs during the mixing stage. For more information on compounding techniques, see Encyclopedia of Polymer Science and Engineering, Vol. 4, p. See 66 (reference) (formulation).

  In a further step g), the nanocomposite material obtained by step f) may be cured, for example, using conventional curing systems such as sulfur, resins and peroxides.

  A preferred curing system is sulfur based. A typical sulfur-based curing system includes (i) a metal oxide, (ii) elemental sulfur, and (iii) at least one sulfur-based accelerator. The use of metal oxides as components in curing systems is well known in the art. A suitable metal oxide is zinc oxide, which is typically used in an amount of about 1 to about 10, preferably about 2 to about 5 parts by weight per hundred parts by weight butyl polymer in the nanocomposite. Elemental sulfur, which constitutes component (ii) of the preferred curing system, is typically used in an amount of about 0.2 to about 10 parts by weight per hundred parts by weight butyl polymer in the composition. Suitable sulfur-based accelerators (preferred curing system component (iii)) are typically used in an amount of about 0.5 to about 3 parts by weight per hundred parts by weight butyl polymer in the composition. Non-limiting examples of useful sulfur-based accelerators include thiuram sulfides such as tetramethylthiuram disulfide (TMTD), thiocarbamates such as zinc dimethyldithiocarbamate (ZDC) and thiazyl such as mercaptobenzothiazyl disulfide (MBTS). And may be selected from benzothiazyl compounds. Preferably, the sulfur-based accelerator is mercaptobenzothiazyl disulfide.

  Cured products are reaction accelerators, vulcanization accelerators, vulcanization accelerators, antioxidants, foaming agents, anti-aging agents, heat stabilizers, light stabilizers, ozone stabilizers, processing aids, plasticizers, and adhesives. Additives, blowing agents, dyes, pigments, waxes, extenders, organic acids, inhibitors, metal oxides, and activators such as triethanolamine, polyethylene glycol, hexanetriol, etc. known to the rubber industry Further, an auxiliary product for rubber may be further contained. The rubber auxiliaries are used in conventional amounts that depend inter alia on the intended use. The cured article may also contain mineral and / or non-mineral fillers. Conventional amounts are 0.1 to 50% by weight, based on rubber.

  More information on the vulcanization process can be found in Encyclopedia of Polymer Science and Engineering, Vol. 17, s. It can be obtained in 666 and below (vulcanization).

  Cured nanocomposites include thermoplastic elastomers, footwear, storage membranes, protective clothing, pharmaceutical stoppers, linings, and barrier coatings as part of tires including but not limited to innerliners, treads, sidewalls, and adhesives. It may be used as part.

Example 1 Polymerization and Distillation The key elements of the process described in FIG. 1 were operated on a pilot scale using a 2 liter total volume reactor operating in continuous mode. The feed to the reactor was 3.87 kg / h isobutene, 0.09 kg / h isoprene and 2.0 kg / h hexane giving a monomer / common aliphatic medium mass ratio of 66:34. The reaction temperature used was −65 ° C. and a solution having a solid content of 16% by weight was produced. This material had a weight average molecular weight of about 440 kg / mol and an isoprene content of about 1.7 mol%. The solution from the reactor was supplied to a 40-tray distillation column to separate the monomer from the rubber solution. The solution was preheated to 42 ° C and a reboiler was used at the bottom to maintain a bottom temperature of 113 ° C. A portion of the overhead stream was returned to the top of the column using a reflux condenser to maintain the temperature there at 36 ° C. The separation achieved in the column left less than 10 ppm of residual isoprene monomer in the separated rubber solution and about 1% common aliphatic medium component in the overhead monomer stream. The separated monomer was purified and then reintroduced into the solution polymerization reactor. The separated rubber solution in the common aliphatic medium was such that bromination could be achieved by conventional methods with the addition of a supplemental common aliphatic medium.

  The common aliphatic medium used is commercially available and contains 97.5% by weight aliphatic hydrocarbons having a boiling point in the range of 45 ° C. to 80 ° C. at a pressure of 1013 hPa, the remainder being 1013 hPa. It was an aliphatic hydrocarbon having a boiling point below 45 ° C or above 80 ° C.

Example 2 Halogenation The separated rubber solution of Example 1 was halogenated using a pilot scale bromination apparatus. An amount of 10% supplementary common aliphatic medium was added to the separated rubber solution to reduce the viscosity. A brominated butyl polymer containing 1.6% bromine is prepared in a separate rubber solution. The halogenated separated rubber solution is then finished using conventional drying and finishing techniques.

Example 3-Preparation of phosphonium ionomer nanocomposite In a 2 L Parr reactor, 100 g of bromobutyl rubber of Example 2 is dissolved in 1000 mL of hexane. To this, 4 g of triphenylphosphine and 10 g of nanoclay (Cloisite ^™ 15A) are added and allowed to react at a temperature of 100 ° C. for 60 minutes. The polymer cement is solidified in ethanol and the resulting polymer nanocomposite is dried and analyzed by ¹ H and ³¹ P NMR. A high ionomer content was confirmed. Nanoclay peeling was confirmed by X-ray diffraction analysis.

Example 4-Preparation of ammonium ionomer nanocomposite In a 2 L Parr reactor, 100 g of bromobutyl rubber of Example 2 is dissolved in 1000 mL of hexane. To this, 3.2 g N, N-dimethylaminoethanol and 10 g nanoclay (Cloisite ^™ 15A) are added and allowed to react at a temperature of 100 ° C. for 60 minutes. The polymer cement is solidified in ethanol and the resulting polymer nanocomposite is dried and analyzed by ¹ H NMR. A high ionomer content was confirmed. Nanoclay peeling was confirmed by X-ray diffraction analysis.

  The foregoing merely describes certain preferred embodiments, and other features and aspects of the invention will be apparent to those skilled in the art. Variations and equivalents of the described elements that function similarly may be substituted without affecting the manner in which the invention functions. The inventor intends that all sub-combinations of the described features fall within the scope of the following claims.

Claims (19)

a) 40:60 to 95: 5, preferably 50:50 to 85:15, more preferably 61:39 to 80:20 by weight ratio of monomer mixture to common aliphatic medium,
A common aliphatic medium comprising at least 50% by weight of one or more aliphatic hydrocarbons having a boiling point in the range of 45 ° C. to 80 ° C. at a pressure of 1013 hPa, and at least one monoolefin monomer, at least one multiolefin Providing a reaction medium comprising a monomer mixture comprising monomers and no or at least one other copolymerizable monomer;
b) polymerizing the monomer mixture in the reaction medium to form a rubber solution comprising a rubber polymer at least substantially dissolved in the common aliphatic medium and the medium comprising residual monomers of the monomer mixture. When;
c) separating the residual monomer of the monomer mixture from the rubber solution to form a separated rubber solution comprising the rubber polymer and the common aliphatic medium;
d) brominating the rubber polymer in the separated rubber solution to obtain a solution containing the brominated rubber polymer and the common aliphatic medium;
e) reacting the brominated rubber polymer obtained in step d) with at least one nitrogen and / or phosphorus-containing nucleophile; f) adding a filler to the ionomer obtained in step e), A method of producing a polymer nanocomposite comprising at least a step of mixing a filler and the ionomer to form an uncured nanocomposite.   The method of claim 1, wherein the rubber is butyl rubber.   The monomer mixture comprises at least one isoolefin monomer in the range of 80.0 wt% to 99.9 wt% and at least one multiolefin monomer in the range of 0.1 wt% to 20.0 wt%. The method according to 1 or 2.   The method according to any one of claims 1 to 3, wherein the isoolefin monomer is isobutene and the multiolefin monomer is isoprene.   5. The common aliphatic medium comprises at least 80 wt% of one or more aliphatic hydrocarbons having a boiling point in the range of 45 ° C. to 80 ° C. at a pressure of 1013 hPa. the method of.   The method according to any one of claims 1 to 5, wherein the process temperature of step b) is in the range of -100 ° C to -40 ° C.   The process according to any one of claims 2 to 6, wherein the weight average molecular weight of the butyl rubber measured before bromination is in the range of 200 to 1000 kg / mol.   The process according to any one of claims 1 to 7, wherein the reaction is carried out in a polymerization reactor and the viscosity of the solution upon discharge from the polymerization reactor is less than 2000 cP.   9. A process according to any one of the preceding claims, wherein the rubber solution obtained after step b) has a solids content in the range of 3 to 25%.   10. A process according to any one of claims 1 to 9, wherein molecular bromine is used as brominating agent.   11. A process according to any one of claims 1 to 10, wherein the amount of brominating agent used is in the range of 0.1 to 20% by weight of the rubber.   The method according to any one of claims 1 to 11, wherein the brominating agent is used in combination with an oxidizing agent. Said nitrogen and / or phosphorus containing nucleophile is of formula I
AR ¹ R ² R ³ (I), (wherein
A means nitrogen or phosphorus,
R ¹ , R ² and R ³ are independently selected from the group consisting of C ₁ -C ₁₈ alkyl, C ₆ -C ₁₅ arylalkyl or C ₅ -C ₁₄ aryl)
13. The method according to any one of claims 1 to 12, wherein   14. A method according to any one of claims 1 to 13, wherein steps e) and f) are performed simultaneously.   15. A method according to any one of the preceding claims, wherein the filler is selected from the group of high aspect ratio fillers.   16. A method according to any one of the preceding claims, wherein the filler has a BET surface area of 5 to 200 square meters per gram, measured according to DIN (Deutsche Industry Norm) 66131. .   17. A method according to any one of claims 1 to 16, wherein the nanocomposite material is cured in a further step g).   Use of a nanocomposite material produced according to any one of claims 1 to 17 for producing a cured nanocomposite material.   17. Nanocomposites or claims made according to any one of claims 1-16 as part of a tire, adhesive, thermoplastic elastomer, footwear, storage membrane, protective garment, pharmaceutical stopper, lining, and barrier coating. Use of cured nanocomposites made according to 17.

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